The tunnel field-effect transistor (TFET) is a candidate of future transistor due to its steep-slope switch properties and the resulting advantages in ultra-low-power electronic applications. Since subthreshold swing (SS) of TFET is not limited by thermal factor, lowering VDD is achievable without performance degradation in device shrinkage rule.
Vertical transistor architecture is widely used for building TFET circuits. However, this approach has its own challenges including the design and fabrication of the bottom contact. It is a complicated integration flow for vertical TFET. In addition, the on-state current is conflict with device area.